Evaluation of a large-scale bridge strain, temperature and crack monitoring with distributed fibre optic sensors

Royal Institute of Technology (KTH), Stockholm, Sweden
06/2011; 1(1):37-46. DOI: 10.1007/s13349-011-0004-x

ABSTRACT Many structures like bridges are ageing and the necessity to measure the uncertain parameters is relevant. Crack-related parameters
can be measured with traditional techniques like crack gauges and displacement transducers. A method that can detect and localise
cracks as well as measure crack width is most favourable. Several distributed and quasi-distributed systems were introduced
to the market and tested in recent years. This paper presents a large-scale Structural Health Monitoring project based on
stimulated Brillouin scattering in optical fibres for an old bridge. The Götaälv Bridge is a continuous steel girder bridge
with concrete bridge deck. Steel girders suffer from fatigue and mediocre steel quality and some severe cracking and also
a minor structural element collapse have taken place. The system installed on the bridge measures strain profiles along the
whole length of the bridge and detects cracks that are wider than 0.5mm. Procedures like factory acceptance test, site acceptance
test, laboratory testing and field testing are presented and analysed. Innovative technology was developed, tested and applied
on the bridge. Heuristic knowledge was collected; conclusions are presented and discussed for future development.

KeywordsBridges–Field testing and monitoring–Maintenance and inspection

  • [Show abstract] [Hide abstract]
    ABSTRACT: Structural health monitoring has become a viable solution to monitor critical infrastructure components that show distress or are unable to pass current load ratings. This research introduces the concept of a composite layer bonded to concrete structures, which is capable of providing distributed sensing capabilities. The layer consists of carbon nanotubes that are deposited on a carrier, which form a continuous conductive skin that is exceptionally sensitive to changes in strain and the formation and propagation of micro-damage and macro-damage. It can be either structural, where the layer represents the reinforcement as well as the sensor, or nonstructural, where the layer acts as a sensing skin alone. Distributed sensing allows for increased detectability of forming or growing damage that cannot necessarily be captured with conventional point-type sensors such as strain gages or accelerometers. Once developed, this sensing skin may be able to give real-time feedback on changes in strain, temperature effects, and formation and propagation of damage. In this article, we present the fabrication and evaluation of an integrated structural sensing composite layer attached to a concrete beam specimen. The specimen was tested to failure in the laboratory. Experimental results are presented and discussed, and currently ongoing research is introduced.
    Journal of Intelligent Material Systems and Structures 09/2013; 25(11):1331-1339. DOI:10.1177/1045389X13505252 · 2.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a method to obtain crack initiation, location and width in concrete structures subjected to bending and instrumented with an optical backscattered reflectometer (OBR) system is proposed. Continuous strain data with high spatial resolution and accuracy are the main advantages of the OBR system. These characteristics make this structural health monitoring technique a useful tool in early damage detection in important structural problems. In the specific case of reinforced concrete structures, which exhibit cracks even in-service loading, the possibility to obtain strain data with high spatial resolution is a main issue. In this way, this information is of paramount importance concerning the durability and long performance and management of concrete structures. The proposed method is based on the results of a test up to failure carried out on a reinforced concrete slab. Using test data and different crack modeling criteria in concrete structures, simple nonlinear finite element models were elaborated to validate its use in the localization and appraisal of the crack width in the testing slab.
    Smart Materials and Structures 03/2015; 24(3):035005. DOI:10.1088/0964-1726/24/3/035005 · 2.45 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rubble mound breakwaters are coastal defense structures that protect harbors and beaches from the impacts of both littoral drift and storm waves. They occasionally break, leading to catastrophic damage to surrounding human populations and resulting in huge economic and environmental losses. Ensuring their stability is considered to be of vital importance and the major reason for setting up breakwater monitoring systems. Terrestrial laser scanning has been recognized as a monitoring technique of existing infrastructures. Its capability for measuring large amounts of accurate points in a short period of time is also well proven. In this paper we first introduce a method for the automatic extraction of face geometry of concrete cubic blocks, as typically used in breakwaters. Point clouds are segmented based on their orientation and location. Then we compare corresponding cuboids of three co-registered point clouds to estimate their transformation parameters over time. The first method is demonstrated on scan data from the Baiona breakwater (Spain) while the change detection is demonstrated on repeated scan data of concrete bricks, where the changing scenario was simulated. The application of the presented methodology has verified its effectiveness for outlining the 3D breakwater units and analyzing their changes at the millimeter level. Breakwater management activities could benefit from this initial version of the method in order to improve their productivity.
    06/2014; II-5:385-391. DOI:10.5194/isprsannals-II-5-289-2014


1 Download
Available from